For more than 100 years, there has been an ongoing search for chemicals that are effective decontaminants, preservatives and fixatives, but which are not seriously dangerous to people and the environment. In particular, compounds are desired that are effective fixatives for biological materials, effective preservatives in embalming procedures, effective agents for viral and microbial decontamination, and effective stabilizers for biological materials like cells, tissues, organs, organisms and bodies.
Also, chemicals have been sought which are effective for decontaminating non-biological materials and objects such as equipment, supplies, instruments, tools, probes, work surfaces, packing supplies, walls, floors, and the like in medical, surgical, food processing, pharmaceutical processing, and other areas where viral and microbial decontamination is important.
One particularly effective group of chemicals that has these desired activities are the aldehydes (see, e.g., U.S. Pat. Nos. 4,343,617 and 4,820,504). Conventionally, aldehydes such as glutaraldehyde and formaldehyde have been used because they interact strongly with biological materials and they cross-link proteins and nucleic acids. Glutaraldehyde is a dialdehyde having an aldehyde group on either end of a propane backbone. It is the two aldehyde groups on either end of the molecule that cause the cross-linking in biological materials and which are responsible for fixation.
Formaldehyde is a monoaldehyde (CH.sub.2 O) which reacts with biological material just like a dialdehyde by cross-linking. The mechanism of formaldehyde cross-linking is believed to occur in a 2-step reaction wherein formaldehyde first reacts with a reactive hydrogen, such as a non-ionized hydrogen attached to the amino group of a protein, to form a reactive intermediate. The reactive intermediate then reacts with a second reactive hydrogen to form a methylene bridge (cross-link) between the two reaction sites plus water. These reactions are depicted as follows: EQU (1) R--H+HCHO.fwdarw.[R--CH.sub.2 OH] EQU (2) [R--CH.sub.2 OH]+R'--H.fwdarw.R--CH.sub.2 --R'+H.sub.2 O
wherein R and R' are a protein, nucleic acid, or other structure containing a reactive hydrogen. As shown above, formaldehyde can be conceptualized as being a one-carbon dialdehyde.
On the negative side, however, all of the aldehydes that have been used to obtain these desired activities (as noted above) are extremely dangerous to people and to the environment, so much so that their use has been curtailed severely by governmental agencies. Further, these parallel observations of efficacy and dangerousness have led, over the years, to the generally-accepted conclusion that aldehyde reactivity is directly and inseparably linked to the relatively dangerous effects that they have on people, on other forms of life, and on the environment.
However, the present inventor unexpectedly discovered that certain dialdehydes are as active as formaldehyde and glutaraldehyde, yet they are relatively safer to people and the environment. It is this discovery that now will allow certain specific, dialdehydes to be developed and used for the critically needed activities described above. In the absence of this discovery, these dialdehydes would not be developed for commercial use because conventional wisdom has predicted that they, like formaldehyde and glutaraldehyde, would be too dangerous to people. It would have been expected under conventional wisdom that these dialdehydes eventually would be either curtailed, or banned by various governmental agencies. The present invention makes it possible to safely use this important sub-group of dialdehydes as decontaminating agents, tissue fixatives, preservatives, and embalming agents.